Daylight time. How long is a light year in space?

One way or another, in my Everyday life we measure distances: to the nearest supermarket, to a relative’s house in another city, to and so on. However, when it comes to the vastness of outer space, it turns out that using familiar values ​​like kilometers is extremely irrational. And the point here is not only in the difficulty of perceiving the resulting gigantic values, but in the number of numbers in them. Even writing so many zeros will become a problem. For example, the shortest distance from Mars to Earth is 55.7 million kilometers. Six zeros! But the red planet is one of our closest neighbors in the sky. How to use the cumbersome numbers that result when calculating the distance even to the nearest stars? And right now we need such a value as a light year. How much is it equal? Let's figure it out now.

The concept of a light year is also closely related to relativistic physics, in which the close connection and mutual dependence of space and time was established at the beginning of the 20th century, when the postulates of Newtonian mechanics collapsed. Before this distance value, larger scale units in the system

were formed quite simply: each subsequent one was a collection of units of a smaller order (centimeters, meters, kilometers, and so on). In the case of a light year, distance was tied to time. Modern science It is known that the speed of light propagation in a vacuum is constant. Moreover, she is maximum speed in nature, acceptable in modern relativistic physics. It was these ideas that formed the basis of the new meaning. A light year is equal to the distance a ray of light travels in one Earth calendar year. In kilometers it is approximately 9.46 * 10 15 kilometers. Interestingly, a photon travels the distance to the nearest Moon in 1.3 seconds. It's about eight minutes to the sun. But the next closest stars, Alpha, are already about four light years away.

Just a fantastic distance. There is an even larger measure of space in astrophysics. A light year is equal to about one-third of a parsec, an even larger unit of measurement of interstellar distances.

Speed ​​of light propagation under different conditions

By the way, there is also such a feature that photons can at different speeds spread into different environments. We already know how fast they fly in a vacuum. And when they say that a light year is equal to the distance covered by light in a year, they mean exactly the empty space. However, it is interesting to note that under other conditions the speed of light may be lower. For example, in air, photons scatter at a slightly lower speed than in vacuum. Which one depends on the specific state of the atmosphere. Thus, in a gas-filled environment, the light year would be somewhat smaller. However, it would not differ significantly from the accepted one.

As you know, to measure the distances from the Sun to the planets, as well as between the planets, scientists came up with an astronomical unit. What is it light year?

First of all, it should be noted that the light year is also a unit of measurement adopted in astronomy, but not of time (as it might seem, judging by the meaning of the word “year”), but of distance.

What is a light year equal to?

When scientists managed to calculate the distances to the nearest stars, it became obvious that in starry world The astronomical unit is inconvenient to use. Let's say for starters that the distance from the Sun to the nearest star is approximately 4.5 light years. This means that light from our Sun to the nearest star (by the way, it is called Proxima Centauri) takes 4.5 years to travel! How far is this distance? Let’s not bore anyone with mathematics, let’s just note that in a second, particles of light fly 300,000 kilometers. That is, if you send a signal with a flashlight towards the Moon, this light will be seen there in less than a second and a half. Light travels from the Sun to Earth in 8.5 minutes. How long then do the rays of light travel in a year?

Let's say right away: a light year is approximately 10 trillion kilometers(a trillion is one followed by twelve zeros). More precisely, 9,460,730,472,581 kilometers. If recalculated in astronomical units, it will be approximately 67,000. And this is only for the nearest star!

It is clear that in the world of stars and galaxies the astronomical unit is not suitable for measurements. It is easier to operate in calculations with light years.

Applicability in the stellar world

For example, the distance from Earth to the brightest star in the sky, Sirius, is 8 light years. And the distance from the Sun to the North Star is about 600 light years. That is, light from us gets there in 600 years. This would be approximately 40 million astronomical units. For comparison, we point out that the size (diameter) of our Galaxy is milky way- about 100,000 light years. Our closest neighbor, a spiral galaxy called the Andromeda Nebula, is 2.52 million light years away from Earth. It is very inconvenient to indicate this in astronomical units. But there are objects in the Universe that are generally 15 billion light years away from us. Thus, the radius of the observable Universe is 13.77 billion light years. And the complete Universe, as is known, extends beyond the observable part.

By the way, the diameter of the observable Universe is not at all 2 times larger than the radius, as you might think. The thing is that over time, space expands. Those distant objects that emitted light 13.77 billion years ago have flown even further away from us. Today they are more than 46.5 billion light years away. Doubling this gives us 93 billion light years. This is the true diameter of the observable Universe. So the size of the part of space that is being observed (and which is also called the Metagalaxy) is increasing all the time.

Measuring such distances in kilometers or astronomical units makes no sense. To be honest, light years don’t quite fit here either. But nothing better people haven't figured it out yet. The numbers are so huge that only a computer can handle them.

Definition and essence of light year

Thus, light year (light year) is a unit of length, not time, which represents the distance traveled by a solar ray in a year, that is, in 365 days. This unit of measurement is very convenient for its clarity. It allows you to answer the question, after what period of time you can expect a response if you send an electromagnetic message to a certain star. And if this period is too long (for example, a thousand years), then there is no point in such actions.

Surely, having heard in some science fiction action movie an expression a la “twenty to Tatooine light years", many asked legitimate questions. I'll mention some of them:

Isn't a year a time?

Then what is it light year?

How many kilometers is it?

How long will it take to overcome light year spaceship With Earth?

I decided to devote today’s article to explaining the meaning of this unit of measurement, comparing it with our usual kilometers and demonstrating the scale that it operates Universe.

Virtual racer.

Let's imagine a person, in violation of all the rules, rushing along a highway at a speed of 250 km/h. In two hours it will cover 500 km, and in four – as much as 1000. Unless, of course, it crashes in the process...

It would seem that this is speed! But in order to go around the whole Earth(≈ 40,000 km), our racer will need 40 times more time. And this is already 4 x 40 = 160 hours. Or almost a whole week of continuous driving!

In the end, however, we will not say that he covered 40,000,000 meters. Because laziness has always forced us to invent and use shorter alternative units of measurement.

Limit.

From a school physics course, everyone should know that the fastest rider in Universe- light. In one second, its beam covers a distance of approximately 300,000 km, and thus it will circle the globe in 0.134 seconds. That's 4,298,507 times faster than our virtual racer!

From Earth before Moon the light reaches on average 1.25 s, up to Sun its beam will reach in a little more than 8 minutes.

Colossal, isn't it? But the existence of speeds has not yet been proven, high speed Sveta. That's why scientific world decided that it would be logical to measure cosmic scales in units that a radio wave (which light, in particular, is) travels over certain time intervals.

Distances.

Thus, light year- nothing more than the distance that a ray of light travels in one year. On interstellar scales, using distance units smaller than this does not make much sense. And yet they are there. Here are their approximate values:

1 light second ≈ 300,000 km;

1 light minute ≈ 18,000,000 km;

1 light hour ≈ 1,080,000,000 km;

1 light day ≈ 26,000,000,000 km;

1 light week ≈ 181,000,000,000 km;

1 light month ≈ 790,000,000,000 km.

Now, so that you understand where the numbers come from, let’s calculate what one is equal to light year.

There are 365 days in a year, 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute. Thus, a year consists of 365 x 24 x 60 x 60 = 31,536,000 seconds. In one second, light travels 300,000 km. Therefore, in a year its beam will cover a distance of 31,536,000 x 300,000 = 9,460,800,000,000 km.

This number reads like this: NINE TRILLION, FOUR HUNDRED AND SIXTY BILLION AND EIGHT HUNDRED MILLION kilometers.

Of course, the exact meaning light years slightly different from what we calculated. But when describing distances to stars in popular science articles The highest precision is not needed in principle, and a hundred or two million kilometers will not play a special role here.

Now let's continue our thought experiments...

Scale.

Let's assume that modern spaceship leaves solar system with the third escape velocity (≈ 16.7 km/s). First light year he will overcome it in 18,000 years!

4,36 light years to the closest star system to us ( Alpha Centauri, see the image at the beginning) it will overcome in about 78 thousand years!

Our Milky Way galaxy, having a diameter of approximately 100,000 light years, it will cross in 1 billion 780 million years.

A light year is the distance that light travels in one year. The International Astronomical Union gave its explanation light year- this is the distance that light travels in a vacuum, without the participation of gravity, in a Julian year. The Julian year is equal to 365 days. It is this decoding that is used in scientific literature.

If we take professional literature, then the distance is calculated in parsecs or kilo- and megaparsecs.

There are specific numbers that determine the distance of light hours, minutes, days, etc.

• A light year is equal to 9,460,800,000,000 km,
• month- 788,333 million km.,
• a week- 197,083 million km.,
• day- 26,277 million km,
• hour- 1,094 million km.,
• minute- about 18 million km.,
• second- about 300 thousand km.

This is interesting! From the Earth to the Moon, light travels on average in 1.25 seconds, while its beam reaches the Sun in just over 8 minutes.

The star Betelgeuse in the constellation Orion should explode in the foreseeable future (in fact, within a few centuries).

Betelgeuse is located at a distance of 495 to 640 light years from us.
If it explodes right now, then the inhabitants of the Earth will see this explosion only in 500-600 years.

And if you see an explosion today, then remember that in fact the explosion occurred around the time of Ivan the Terrible...

Earth year

An earthly year is the distance traveled by the earth in one year. If we take into account all the calculations, then one light year is equal to 63242 Earth years. This figure applies specifically to planet Earth; for others, such as Mars or Jupiter, they will be completely different. A light year measures the distance from one celestial object to another. The numbers for light years and earth years are so different, although they mean distance.

Scale

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Sources

Quick answer: not at all.

We are often asked very interesting questions, the answers to which are very non-standard.

You see one of these questions in the title. And really, how many earthly years are there in one bright year? You may be disappointed, but there is no real answer.

The fact is that a bright year is not a measure of time, but a distance measure. To be more precise, a light year is the distance of distance in a vacuum without gravity fields, one effect of the Julian year (equivalent to 365.25 standard days per 86,400 SI seconds or 31,557,600 seconds) by the International Astronomical Federation.

To do this, we take the 300 thousand kilometers per second mark (that's exactly the speed of light) and multiply it with 31.56 million seconds (many seconds per year) and we get a huge number - 9460800000 000 km (or 9.46 million kilometers). This fantastic number means a distance equal to a light year.

• 1 light month ~ 788,333,000,000 km

• 1 easy week ~ 197,083,000 km

• 1 daylight ~ 26,277 million km

• 1 light hour ~ 1,094 million km

• 1 light minute ~ about 18 million km

• 1 light second ~ 300 thousand km

To find out how many kilometers in a light year you need to use a simple web calculator.

In the left box, enter the number of light years of interest you want to convert. In the field on the right you will see the calculation result. Simply click the appropriate link to convert light years or miles to other units.

What is “bright summer”

The light year of the one-way system (St., ly) is equal to the distance traveled by light in a vacuum in one July year (365.25 days).

This term is mainly used in science and fiction, and in the professional environment the term “parsecs” with the prefix “kilo” and “mega” was adopted.

and not before 1984, according to the bright year, to understand the distance with light traveled in the tropical year, now the value has changed by 0.002%, and the practical value of this difference, because very precise measurements are not produced in light years. The speed of light is about 300 thousand.

km per second and a luminous year of about 10 trillion kilometers (9460.8800 million km). Regarding distances, for example, Sirius is 8 light years from its closest proximity to the star Proxima Centauri - 4.22 light years, and the diameter of the Roman road - our galaxy, which is 100,000 light years.

What is a "kilometer"

The kilometer kilometer (km, km) is a plural unit of reference distances, widely used throughout the world.

One kilometer 1000 meters, 0.621 miles, 0.9374 miles, 1094 yards, 3281 meters, 1.057 x 10 - 13 light years, 6.67 x 10 - 9 astronomical units.

Easy years

For hundreds of years, people have been inventing their own planet to invent more and more remote sensing systems. Therefore, it was decided to take into account universal unit one meter long and a long measuring path in kilometers.

But in the next twentieth century, this created a new problem for humanity. People began to carefully study the universe - and it turned out that the size of the universe is so large that miles are simply not suitable here.

In ordinary units you can express the distance from the Earth to the Moon or from the Earth to Mars. But if you're trying to figure out how far the nearest star is from our planet, the number "grows" with an imperceptible number of characters per decimal point.

What is 1 light year?

It was obvious that a new space exploration unit was needed - and it was a bright year.

In a second, light travels 300,000 kilometers. Easy years — this is the distance whose light will travel exactly a year, and when translated into a more familiar system of numbers, this distance is 9,460,730,472,580.8 kilometers. It is clear that using a concise “simple flight” is much more convenient than using every huge number in the calculations.

Of all the stars closest to us, Proxima Centauri was only “4.2 light years away.” Of course, based on kilometer data there is an unimaginable amount. However, everything is relative - considering that the nearest Andromeda galaxy is separated from the Roman road by as much as 2.5 million light years, the star and the truth begin to seem very close neighbors.

By the way, using light years helps scientists understand in which corners of space it is reasonable to find intelligent life and where sending radio signals is completely useless.

After all, the speed of a radio signal is similar to the speed of light, so a greeting sent towards a distant galaxy would take millions of years to reach its destination. It makes sense to expect a response from neighboring “neighbors” - objects whose hypothetical response signals will reach ground-based devices even during a person’s lifetime.

1 light year - how many Earth years?

There is a common misconception that a light year is a unit of time.

Actually this is not true. This term has nothing to do with Earth years, it does not refer to them and only represents the distance that light travels in one Earth year.

Whatever lifestyle we lead, whatever we do, one way or another, we use some units of measurement every day. We ask for a glass of water, heat our own breakfast to a certain temperature, visually estimate how far we need to walk to the nearest post office, arrange a meeting at a certain time, and so on. All these actions require

Not just calculations, but also a certain measurement of various numerical categories: distance, quantity, weight, time and others. We use numbers regularly in our daily lives. And we have long been accustomed to these numbers, as if to some kind of instruments. But what happens when we get out of our everyday comfort zone and encounter something unusual for us? numerical values? In this article we will talk about the fantastic figures of the Universe.

Universal spaces

The situation with cosmic distances is even more surprising. We are fully aware of the kilometers to the neighboring city and even from Moscow to New York. But it is difficult to visualize distances when it comes to the scale of star clusters. It is now that we will need the so-called light year. After all, the distances even between neighboring stars are extremely large, and measuring them in kilometers or miles is simply irrational. And here the matter is not only in the difficulty of perceiving the huge resulting numbers, but in the number of their zeros. It becomes a problem to write the number. For example, the distance from Earth to Mars during the period of closest approach is 55.7 million kilometers. A value with six zeros. But Mars is one of our closest cosmic neighbors! The distance to the nearest star other than the Sun will be millions of times greater. And then, whether we measured it in kilometers or miles, astronomers would have to spend hours of their time just recording these gigantic quantities. A light year solved this problem. The solution was quite ingenious.

What is a light year equal to?

Instead of inventing a new unit of measurement, which is the sum of units of a smaller order (as happens with millimeters, centimeters, meters, kilometers), it was decided to tie distance to time. Actually, the fact that time is also a physical field influencing events is more

Moreover, interconnected and convertible with space, it was discovered by Albert Einstein and proven through his theory of relativity. The speed of light became constant. And the passage of a certain distance by a light beam per unit of time gave new physical spatial quantities: light second, light minute, light day, light month, light year. For example, per second a beam of light (in space conditions - vacuum) travels a distance of approximately 300 thousand kilometers. It is easy to calculate that one light year is equal to approximately 9.46 * 10 15. Thus, the distance from the Earth to the nearest cosmic body, the Moon, is a little more than one light second, and to the Sun is about eight light minutes. Marginal bodies solar system according to modern ideas, they orbit at a distance of one light year. The next closest star to us, or rather, a system of double stars, Alpha and Proxima Centauri, is so far away that even the light from them reaches our telescopes only four years after its launch. And these are still the celestial bodies closest to us. Light from the other end of the Milky Way takes more than a hundred thousand years to reach us.